By adding a strong acid to the buffer solution,the $pH$ of the buffer solution

Assertion : Mixture of $CH_3COOH$ and $CH_3COONH_4$ is an example of acidic buffer.
Reason : Acidic buffer contains equimolar mixture of a weak acid and its salt with weak base.

Which of the following buffers is used to maintain the $pH$ of human blood naturally?

Which of the following is not a buffer solution?

The $pH$ of a buffer solution containing $0.2 \ mol/L$ $CH_3COONa$ and $1.5 \ mol/L$ $CH_3COOH$ is ($K_a$ for acetic acid is $1.8 \times 10^{-5}$).

How to prepare a buffer solution using ammonia $(pK_b = 4.75)$? What is the $pH$ of this buffer if the concentrations of ammonia and ammonium chloride are equal?